1. Field of the Invention
The present invention relates to a system for lubricating the rails of a railway track, and more specifically, to an actuator element which is located on or in the ground next to the rails to be lubricated and which is activated by the passing of the wheels of a railway vehicle thereby. In particular, the present invention is directed to an improved actuator element of such a lubricating system operated by the internal circulation of a hydraulic fluid.
2. Description of the Background Art
Lubricating devices that are positioned next to the rails of a railway track and that are activated by the passage of the wheels of the railway vehicle to discharge a lubricant onto the rail head are well known. The application of lubricant to the rails has been found to reduce the frictional wear on the railhead and the degree of noise between the flanges of the wheels and the railhead. Many of the known lubricating devices include a lubricant supply tank located in the ground near the rail, one or more lubricant distributing elements positioned on one side of the rail, a pump in the supply tank for conveying lubricant through one or more pipes to the lubricant distributing elements positioned on one side of the rail, and an actuator element located along the length of the rail. The actuator element is suitably connected to the pump and operates the pump in response to the passage of the wheels of the railway vehicle over the actuator element.
In some of the present-day lubricating devices, the connection between the actuator element and the pump in the supply tank is mechanical, involving an elongated rotatable drive rod with attendant joints, springs, bearings, etc. However, over time, these mechanical elements deteriorate due to wear and tear. Additionally, in order to function these lubricating devices must be located above the ground next to the rail. This location of these devices generally results in damage to the devices particularly when the railway vehicle derails or when rail equipment is dragged along the tracks. From this, it can easily be appreciated that a lubricating device using a mechanical connection is often undesirable.
Further known lubricating devices include a connection between the actuator element and the pump in the supply tank that consists of either a single hydraulic fluid line or a recirculating fluid loop in which hydraulic fluid, such as light oil is caused to flow by the activation of the actuator element. An example of a lubricating device consisting of a single hydraulic fluid line is disclosed in U.S. Pat. No. 2,355,241 to Rodman, et al. In this device, the actuator element and the pump both function by the expansion and contraction of bellows. These bellows tend to break down over time due to the experienced expansion and contraction stresses. This results in costly replacement of the lubricating device.
An example of a lubricating device consisting of a recirculating fluid loop is disclosed in U.S. Pat. No. 2,401,303 to Huber. In this type of lubricating device, the construction of the actuator element is complicated, and therefore, expensive and difficult to service. The pump, being in the form of a gun pump, has an intricate internal mechanism that frequently breaks down.
U.S. Pat. No. 4,334,596 to Lounsberry discloses a lubricating apparatus for the rail of a railway track which is simpler in design compared to those of the known art discussed herein above. The lubricating system employs a hydraulic fluid recirculating loop between the actuator element and the lubricant pump in the lubricant-containing supply tank. The lubricant pump is a combined gear drive-gear pump device where the gear drive is driven by the flow of hydraulic fluid there through and the gear pump is driven by the gear drive so as to force lubricant from the supply tank to the lubricant distributing elements mounted on the rail.
The actuator element of the above U.S. Pat. No. 4,334,596 has an upper coil spring located between a plunger and a piston, and a lower coil spring located between the piston and a plug located at the bottom of an elongated block. Hydraulic fluid is forced into and out of the chamber of the actuator element upon movement of the piston and plunger. When the fluid is forced out of the actuator element, it actuates a lubricating system that delivers lubricant to the rail.
There are several disadvantages associated with the actuator element of the above U.S. Pat. No. 4,334,596. The input and output lines for the hydraulic fluid are in communication with the lower part of the chamber where the piston generally keeps the fluid in this lower part of the chamber. When the actuator element is new, little or no lubrication travels to the upper part of the chamber whereby the frictional forces between the plunger and the bore wall tend to interfere or decrease the power in the system that is generated on the down stroke of the piston. After wear of the piston, the fluid seeps up between the piston and the chamber wall and into the top part of the chamber affecting both the power in the down stroke and in the up stroke of the piston. Additionally, it has been found that the upper spring, being heavier in construction and the stronger of the two springs, allows for less free travel and develops compression stresses and high fatigue due to the frequent and tremendous forces from the wheels of the rail cars. Failure of the upper spring and the loss of power in the actuator elements result in failure of the lubricating system.
There is, therefore, a need in the art to provide an improved actuator element for a lubricating system that lessens the likelihood of power and/or component failure, i.e. spring failure, so that the performance of the lubricating system for the rail of a railway track is enhanced and maintained.
The present invention has met this need. The invention relates to an actuator element for activating a lubricating system for supplying lubricant to the side of a rail. The actuator element of the invention is used in conjunction with a railway track lubricating apparatus that employs a hydraulic fluid recirculating loop between the actuator element and the lubricant pump.
In a first embodiment of the invention which is used to retrofit existing lubricating system field units, the actuator element comprises a housing with top and bottom surfaces, a hydraulic fluid chamber extending inwardly from the bottom surface of the housing, and a bore communicating between the chamber and the top surface of the housing. The housing includes a radial hydraulic fluid outlet located in the upper part of the chamber and a radial hydraulic fluid inlet opening located in the lower part of the chamber. Both openings are in association with the hydraulic fluid recirculation system whereby hydraulic fluid passes into and out of the chamber of the actuator element. A plunger having a base and a stem is mounted in the housing such that the base is movable along the chamber and the stem is movable along the bore at the top of the housing. An enclosure block is connected at the bottom of the housing and has a stem extending into the chamber toward the plunger. A spacer element is mounted onto the stem of the enclosure block, and in turn, has a stem which positions a coil spring located between the spacer element and the plunger.
When the wheel of a railway vehicle passes over the stem of the plunger, the base of the plunger moves down in the chamber and against the spring. As the stem of the plunger enters the chamber, hydraulic fluid is forced out of the chamber and through the radial hydraulic fluid outlet for operation of a motor pump that delivers lubricant or grease to the lubricant distributing elements mounted on the side of the rail.
When the wheel of the railway vehicle has passed over and clears the stem of the plunger, the spring pushes the base of the plunger upward in the chamber housing and hydraulic fluid is drawn back into the housing chamber of the actuator element.
The diameter of the plunger stem is such that the plunger stem is supported by and is in sealed communication with a bushing. The bushing is in the cavity of the bore and is in communication with the internal wall of the bore. The diameter of the plunger base is such that the plunger base is spaced away from the wall of the chamber. These dimensions for the diameters of the plunger base and wall of the chamber do not create a seal and therefore hydraulic fluid H travels from the hydraulic fluid inlet opening to the hydraulic fluid outlet.
A second embodiment of the invention comprises an actuator element that does not require a spacer element in the housing chamber. This actuator element is preferably employed with newly installed lubricating systems; whereas, the actuator element of the first embodiment is used as a retrofit to existing lubricating systems.
It will be appreciated by those skilled in the art that the present invention provides an improved actuator element for a lubricating apparatus that has a simplified design compared to the actuator elements of the prior art, i.e. one or more components are eliminated, whereby the performance of the lubricating apparatus for the rail of the railway track is enhanced.